In a plasma process, electrical loads designed as electrodes are positioned in a plasma chamber. To stimulate the plasma process, the electrodes are connected to the alternating voltage of a power supply. The electrodes are in contact with so-called targets. The targets consist of a base material on the electrodes e.g., a coating. In a plasma coating process of this type, this base material can be removed from the targets. The targets of such arrangements are usually similar, i.e., they consist of the same material, have substantially the same size and the same construction and are therefore usually supplied with substantially the same power. In the plasma process, the targets are ablated at substantially the same speed. However, slight differences cannot be eliminated. The targets may initially be asymmetrical or become asymmetrical because of ablation during the plasma process. These asymmetries can cause differences in the impedances and burning voltages of the targets. These differences result in different power delivery and different wear periods. This effect can cause one target, which has been worn to a larger extent, to consume more power than other targets, and therefore burn even more quickly. The final result of this effect is that one target is completely burnt while others still have sufficient material. This behavior is highly undesired. Although this problem has been known for a long time, there has been no remedy so far.
It is therefore desirable to provide a method for influencing the power delivery into the electrical loads, and an associated device.
Plasma processes do not always run completely continuously. Impurities, temporally and locally limited charging or other instabilities in the chamber can produce spark-overs in the plasma, so-called arcs, at irregular intervals. These arcs can entail undesired consequences in many cases, such as, e.g., rapid current increase and voltage drops. This can disturb the plasma process, with the consequence of undesired results for target and plasma process. For this purpose, so-called arc management circuits are provided for plasma process power supplies. They stop undesired power delivery in case of such an arc. Upon detection of such an arc, the current supply is generally switched off as quickly as possible or after a defined time period. It is thereby often important to interrupt the power delivery into the plasma process as quickly as possible to protect the power supply, the targets and the objects to be coated.